Power supplies for computing and telecom applications continue to be challenged to supply higher current as system voltages drop. Accordingly, power supplies have gone from single phase to multiple phase topologies. To produce a single output voltage in a multi phase design, several power stages, or phases, are paralleled together such that the current from each phase is summed to produce the desired output current. For n stages in parallel, one of the phases will start its period every 360/n electrical degrees. This technique reduces component stress compared to the single phase solution, and enjoys other benefits such as reducing output voltage ripple for a given capacitor configuration.
A system of this type is shown in copending application Ser. No. 10/392,121, filed Mar. 18, 2003 entitled MULTI-PHASE BUCK CONVERTER in the names of George Schuellein, Dan Clavette and Mark Crowther and assigned to the assignee of the present invention.
To control a multi phase topology, a main controller having multiple outputs is used to supervise the power switches of the phases. For two or three phases, the drivers for the switches are usually integrated into the controller. However, as the number of phases increases, heat produced by the drivers becomes excessive, indicating the desirability to transition to the use of external drivers. This transition takes heat out of the controller and allows the driver to be close to the switches, which increases efficiency, helps with noise immunity of the gate signal, and decreases switching time.
To control more phases, dedicated controllers designed for the exact number of phases can be made, or two-or three-phase controllers can be cascaded. Alternatively, a controller having a flexible method of communicating to the phase drivers would be desirable which would allow any number of phases to be controlled. It would also be desirable to provide a controller that is unique from any other type of controller and wherein the number of phases is selectable by the user. While such a device could be controlled by conventional analog methods common in converters, control of the phases by means of a digital bus would be very desirable.